In known means of this type, under certain unfavorable operating conditions the danger exists that malfunctions, for example, a drop of delivery output, pump overload, or even its failure will occur. These difficulties can occur especially when overly low oil temperatures occur as lubricating oils are being delivered in a lubricant circuit. These operating states prevail, for example, during cold running phases of certain systems, or occur in wind power plants under winter conditions that can last over longer time intervals. The corresponding strong increase in the viscosity of the lubricating oils to be delivered leads at least to a reduction of the delivery output, resulting in danger to the assigned machinery system, or in less favorable cases leads to overloading or even failure of the pump. This situation in turn entails corresponding subsequent damage to the pertinent system.